1. Field of the Invention
The present invention relates to a method for producing a fine structured member and a fine hollow structure, adapted for producing a liquid discharge recording head (also called liquid discharge head) for generating a droplet of a recording liquid to be employed in an ink jet recording method, a method for producing a liquid discharge recording head utilizing the aforementioned method, and a liquid discharge recording method obtained by such method. In particular, the present invention relates to a liquid flow path shape capable of stably discharging a small liquid droplet which realizes a high image quality and also capable realizing a high-speed recording, and also to a technology useful in a method for producing such head.
2. Related Background Art
A liquid discharge head, employed in an ink jet recording method (liquid discharge recording method) for executing recording by discharging a recording liquid such as ink, is generally provided with a liquid flow path, a liquid discharge generation unit provided in a part of such liquid flow path, and a fine recording liquid discharge port (also called “orifice”) for discharging the liquid in the liquid flow path by the thermal energy of the liquid discharge energy generation unit. For producing such liquid discharge recording head, there is conventionally employed, for example:                (1) a method of forming a through hole for ink supply in an element substrate on which a heater for generating thermal energy for liquid discharge and a driver circuit for driving such heater are formed, then executing a pattern formation for constituting walls of the liquid flow path with a photosensitive negative-working resist, and adjoining thereto a a plate in which an ink discharge port is formed by an electroforming method or with an excimer laser; or        (2) a method of preparing an element substrate prepared similarly as in the foregoing method, then separately forming a liquid flow path and an ink discharge port on a resinous film (usually polyimide being advantageously employed) coated with an adhesive material, by an excimer laser, and adjoining thus worked plate having a liquid flow path structure and the aforementioned element substrate under the application of heat and pressure.        
In the ink jet head prepared by the above-described method, a distance, influencing a discharge amount, between the heater and the discharge port should be made as small as possible in order to enable discharge of a very small liquid droplet for achieving a high-quality recording. For this purpose, it is necessary to reduce a height of the liquid flow path, and to reduce the size of a discharge chamber present in a part of the liquid flow path and constituting a bubble generating chamber in contact with the liquid discharge energy generating unit and the size of the discharge port. Thus, in order to enable discharge of a small liquid droplet in the head of the above-mentioned producing method, it is required to form the liquid flow path structured member, to be laminated on the substrate, into a thin film. However, it is extremely difficult to form the liquid flow path structured member in the form of a thin film with a high precision and adhere it to the substrate.
In order to solve the problems in these producing methods, Japanese Patent Publication No. 6-45242 discloses a producing method for an ink jet head, in which a mold for the liquid flow path is patterned with a photosensitive material on a substrate bearing a liquid discharge energy generating element, then a covering resin layer is coated on the substrate so as to cover the mold pattern, then an ink discharge port communicating with the mold of the liquid flow path is formed in the covering resin layer, and then the photosensitive material used for the mold is removed (such method being hereinafter also called “mold casting method”). In such head producing method, a positive-working resist is employed for the ease of removal, as the photosensitive material. This producing method, utilizing the photolithographic technology for semiconductors, enables extremely precise and fine working in forming the liquid flow path, the discharge port etc. However, after the flow path is formed with the positive-working resist and after the positive-working resist is covered with the negative-working film resin, when the negative-working film resin is irradiated with the light corresponding to an absorption wavelength region of such negative-working film resin in order to form the discharge port, the light of such wavelength region also irradiates the pattern formed by the positive-working resist. For this reason, there may result a drawback as a result of a decomposition reaction or the like of the material constituting the pattern formed with the positive-working resist.